1. Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, United Kingdom
2. Astrophysics Research Group, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom
3. Armagh Observatory, College Hill, Armagh, BT61 9DG, United Kingdom
4. Núcleo de Astronomía, Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército 441, Santiago, Chile
5. Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain
6. Departamento de Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain